Going back to the "hotbox" request, now that would be neat! Seeing a hot bearing on a freight car would be an adventure to make it work, but , in the words of Schultx, "Verrry interesting!"
Alan, Yes, Also in the words of Nike, "Just do it". My mind is working overtime, you can probably smell the sawdust burning ! Any ideas?
I was thinking on it....ouch! That hurts the ole brain pan! The LED would need to be behind the bearing plate, so it stands to reason that the axle itself would have to be a dummy that doesn't touch the rail nor roll. It doesn't have to be a very bright LED either, so, maybe there is a way to get one into a rolling truck without the size being obnoxious. The micro LEDs that come prewired are the only way to go, so, hmmmmm. Ponder, ponder.
Fiber optics might be the better way. And yes, Artie Johnson did the "Very Interesting " character, maybe named Schultz?? Or I am probably just confusing it with Hogans Heroes.....
Artie Johnson's character was named Wolfgang, but the character's name isn't mentioned often. Sergeant Schultz was indeed a character on Hogan's Heroes, played by John Banner.
As far as needing resistors to limit current, that's really only necessary if the supply voltage is quite a bit over what the LED can withstand. If you have a 3 volt supply, the LED is only going to use the current it needs. The supply cannot force current into the LED. If the LED starts to draw more current, well, that means it is failing and that's the way it goes. General principle calls for limiting current externally but it's not really necessary in this case. Doug
Yes, I understand all that and I indicated that, on general principles, limiting current externally is desired or even demanded in a lot of circumstances, but, as I said, in this case, supplying these LEDs with small batteries which can only supply a limited current, it's not likely to hurt the LEDs as evidenced by Carl's LEDs not failing in his applications. Doug
You can't be certain of that without first consulting the manufacturer's specification sheets for the LED and the power source. Can you provide a link to them?
I buy bulk 0402 LEDs for about a penny each. White/red/green/yellow. I figured out a way to take single strands of fine gauge wire, stick the LED onto double side tape. Put a small bend in the wire. Tin the bent end. Then, with a magnifier hold the wire in a tweezer, heat the wire about 4 or 5 mm above the tinned part- this will melt the solder. Touch the tinned part to one of the pads on the LED- it will make a joint almost instantly, and repeat. I use these for signal bridge lighting, building lights, street lights, etc. Then, test with a 9V battery and a 2.2 to 3.3kOhm resistor, and mark the positive lead.
Hi Small batteries have voltages that are a function of their chemistry- vary between about 1.2V to about 1.55V. Also, as batteries age, they "crud up" internally- like the battery in your car sulfating over time leading to increased internal resistance, so the voltage at the external contacts will decrease. This is gradual, but will happen with all batteries. So, if you had new silver-oxide batteries in series, you would have 3.1V for a while. Or, if you had two zinc-air batteries, your maximum voltage would only be about 2.7V. The other implied part of your question is - "how long would they last?" The answer is it depends on the application- how much current is required to do what you want. Hope this helps.
Regardless of the life of the LED on a 3v circuit without a resistor I find them too bright myself. I've put a resistor on every LED I've installed to get the light intensity down from what it is when running them at max amperage (that they can handle). If you like them bright then it sounds like you will get away with running them on the edge of their rated amperage. I'd do it because you like the brightness not because of the cost of a resistor as you won't find anything cheaper for your railroad. Sumner
I think what everyone is missing is that Evandesigns 3 volt wall wart will run their LEDS WITHOUT having to use resistors. Description Our 3 Volt 1 amp adapter can run 1 - 50 LEDs and is Guaranteed to correctly run all of our 3 Volt DC LEDs 1 Amp will run from 1 - 50 LEDs 2 Amp will run from 1 - 100 LEDs These regulated adapters will put out exactly 3 Volts of power if you hook one single LED to it, or hook the maximum number of LEDs to it. They are regulated and able to run delicate electronics. These UL listed Adapter / Transformers convert wall current to 3 Volt DC output, perfect for our 3 volt LEDs. Input: AC 120-240V 60HZ 10W Output: Regulated 3V DC 1000mA Center positive .
There is a bit of physics that needs attention. The LEDs may operate at 3V, but for RED this is driving them really hard, shortening their operating life. These curves from Electronics Tutorials explains this: Basically, 3V is OK for Green or Blue. Some white LEDs will not light at less than 3V or be very dim. It is very marginal to operate at 3V for yellow, and not suitable for red or orange. This is because the internal physics of the diode ends up destroying the junction that generates the light. Also, if you tried to run more than 3 or 4 LEDs in series, there would be no light output (or the weakest one might glow slightly). So, implicit in the "3V" operation is all of the LEDs are wired in parallel. It is possible that the company built in a resistor into THEIR "3V" LEDs, the description does not state anything about this or for standard commercial LEDs. If you buy a commercial LED string that runs on low voltage you will see an LED and a corresponding resistor on each LED segment. Having been in opto-electronics and optical communications and laser technology for 40+ years, I suggest that you spend a penny and put a 1/8W 1kOhm to 2kOhm resistor in series with either leg of the LED. This is an important quote from the Evansdesign website: ****These are 3 volt LEDs. They come pre-wired to 8 inches of insulated wire and the correct 3 volt resistors if needed. Note that not every color LED needs a resistor to operate at 3 volts, such as white and blue LEDs.***
The easiest solution would be to use a boxcar to contain all the circuitry powered by a very small battery and the smallest possible light source. Very flexible thin wires run down in front of the bearing box and then a touch of black paint to tone down the light. That way the car can be run in a consist.
